1. Field of Invention
The present invention relates generally to methods for the construction of seepage barriers, and more particularly to a method that utilizes polymer grout to construct anti-seepage curtains with improved impermeability for dams and dikes.
2. Background
The safety of hydraulic infrastructures such as reservoirs is one of the top priority safety concerns. If a reservoir collapses, it could cause a heavy lost of properties or even casualties. Seepage, a problem commonly associated with dams or dikes, is generally considered as a hidden danger. Many dam disasters were caused by the failure of their anti-seepage systems. Various solutions have been proposed ranging from high pressure jet grouting, curtain grouting to impermeable concrete walls. The prior art, however, has significant shortcomings: time consuming, labor intensive, low efficiency, repair-induced structure disturbance or even damage to the dam itself.
High pressure jet grouting applies large energy to the grout with high pressure devices, but the energy is hard to control. Excessive jetting energy could cause punching-shear failure to the soil. It may also cause overall unevenness in strength during the process when the grout is forming. In addition to that, holes may be formed in the soil because the grout takes too long to coagulate.
Curtain grouting presents different kind of problems. Curtain grouting is generally processed by section due to the fact that construction sites are usually massive. Grouting by section gives rise to problems such as uneven thickness in curtain, loose joints between sections, soil debris getting into the joints, insufficient depth, or unwanted sediments formed at the bottom of the curtain walls.
As for the method of constructing impermeable concrete walls, some of its problems include miscalculation in wall structure strength, rush design relying on empirical experience, and construction high cost. Concerns of this nature have limited the wide adoption of impermeable concrete walls. Traditionally, research on impermeable materials has focused on plastic concrete and high strength concrete (reinforced concrete). The high strength concrete may cause high stress due to high elastic modulus whereas the plastic concrete is notorious for its low strength, low impermeability and weak durability. Besides, concrete walls are not water-tight and always come with some degree of water seeping. The prior art has yet to deal with this problem effectively. Needless to say, better impermeable materials or construction methods are needed.
Grouting with polymer, a method developed since 1970s, allows rapid treatment for foundation repair. It has been used to reinforce foundations, fill up hollow spaces underground, or elevate floor by injecting two-component polymer materials into the foundation which then expands under chemical reaction and then coagulates. At present, grout polymer has been applied mostly in foundation repair or road maintenance. No reports have been found on utilizing polymer grout for the construction of anti-seepage curtains for dams and dikes.